//定义函数生成子弹对象
/*
 参数说明:
 kind:子弹的类型(1:单排子弹，2:双排子弹)
 image:存储子弹对应的图片对象
 x:子弹绘制的起始的x坐标
 y:子弹绘制的起始的y坐标
 * */
function Bullet(image,x,y,speed) {
	this.image = image;
	this.x = x;
	this.y = y;
	this.w = 6;
	this.h = 14;
	this.speed = speed;
}
//定义一个函数用来绘制子弹
Bullet.prototype.draw = function() {
	ctx.drawImage(this.image,0,0,this.w,this.h,this.x,this.y,this.w,this.h);
}
//定义函数完成子弹对象的移动
Bullet.prototype.move = function () {
	this.y += this.speed;
}
